APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016;
Baltimore, Maryland
Session V21: Materials at Extremes: Warm Dense Matter
2:30 PM–5:30 PM,
Thursday, March 17, 2016
Room: 320
Sponsoring
Units:
GSCCM DCOMP DMP
Chair: Arianna Gleason, Los Alamos National Laboratory
Abstract ID: BAPS.2016.MAR.V21.1
Abstract: V21.00001 : Study of the Warm Dense Matter with XANES spectroscopy - Applications to planetary interiors
2:30 PM–3:06 PM
Preview Abstract
Abstract
Author:
Adrien Denoeud
(CEA)
With the recent discovery of many exoplanets, modelling the interior of these celestial bodies is becoming a fascinating scientific challenge. In this context, it is crucial to accurately know the equations of state and the macroscopic and microscopic physical properties of their constituent materials in the Warm Dense Matter regime (WDM). Moreover, planetary models rely almost exclusively on physical properties obtained using first principles simulations based on density functional theory (DFT) predictions. It is thus of paramount importance to validate the basic underlying mechanisms occurring for key planetary constituents (metallization, dissociation, structural modifications, phase transitions, etc....) as pressure and temperature both increase\footnote{K. Umemoto et al., Science 311, 983 (2006)}$^{,}$\footnote{D. Hicks et al., Phys. Rev. Lett, 97, 025502 (2006)}.
\\In this work, we were interested in two materials that can be mainly found in the Earth-like planets: silica, or SiO2, as a model compound of the silicates that constitute the major part of their mantles, and iron, which is found in abundance in their cores. These two materials were compressed and brought to the WDM regime by using strong shock created by laser pulses during various experiments performed on the LULI2000 (Palaiseau, France) and the JLF (Livermore, US) laser facilities and on the LCLS XFEL (Stanford, US). In order to penetrate this dense matter and to have access to its both ionic and electronic structures, we have probed silica and iron with time-resolved X-ray Absorption Near Edge Structure (XANES)\footnote{A. Benuzzi-Mounaix et al., Phys. Rev. Lett, 107, 165006 (2011)}. In parallel with these experiments, we performed quantum molecular dynamics simulations based on DFT at conditions representative of the region investigated experimentally so as to extract the interesting physical processes and comprehend the limits of the implemented models\footnote{V. Recoules et al., Phys. Rev. B, 80, 064110 (2009)}. In particular, these works allowed us to highlight the metallization processes of silica in temperature\footnote{A. Denoeud et al., Phys. Rev. Lett, 113, 116404 (2014)} and the structural changes of its liquid in density, as well as to more constrain the melting curve of iron at very high pressures.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.V21.1